1. Field of the Invention
The invention is directed to an apparatus for the laser processing of workpieces having processing surfaces lying diametrically opposite one another.
2. Description of the Prior Art
In the manufacture of fine surface structures, for example in printed circuit boards, it is known to structure conductive or cover layers with high precision using a laser beam. Given printed circuit boards laminated on both sides, the printed circuit board must be turned over and be brought into the working range of the laser unit a second time.
U.S. Pat. No. 5,678,229 A has disclosed a laser cutting means for plates, whereby the workpiece is arranged between two laser units directed toward one another and whose optical axes are exactly aligned with one another, so that the displaceable guided plates can be given a clean parting cut.
JP 03142090 A has also discloses a laser drilling means for printed circuit boards, whereby the holes are generated by two laser devices whose laser beams given via fixed deflection mirrors likewise have their optical axes exactly aligned with one another. The printed circuit board must be correspondingly shifted for drilling other holes.
Similarly, JP 60177982 has disclosed a similar device for the simultaneous and both-sided marking of plates, whereby, however, the laser beams are adjusted relative to one another from both sides via a beam splitter and multiple, fixed deflection mirrors.
The invention is based on the object of enhancing the processing precision and shortening the processing duration.
This object is achieved by the invention where two laser units are directed toward one another. These units can be simultaneously operated. Each unit has a deflection device that deflects the laser beam to cover the area of the workpiece to be processed at any time. Since the two laser units can be controlled independently of one another, different patterns can be generated on the two sides without having to move the printed circuit board, as a result whereof the processing time is cut in half. Moreover, the turnover, change and adjustment outlay for processing the second printed circuit board side is eliminated. The position of the workpiece need only be acquired once. The two laser units can be pre-adjusted such that the processing patterns at both sides of the printed circuit board are congruent without differences.
In another embodiment of the present invention, different structures can be produced on the two sides of the printed circuit board without employing masks.